1. Field of the Invention
The present invention relates to a multi-input differential amplifier configured to amplify a difference between multiple inputs and a light emitting element driving device using the multi-input differential amplifier.
2. Description of the Related Art
In a common differential amplifier, one input signal is input to an inverting input terminal thereof, and another input signal is input to a non-inverting input terminal thereof. In such common differential amplifier, it is known that an input offset is canceled by controlling a potential of a back gate of a field-effect transistor constituting the differential amplifier (see Japanese Patent No. 4031447 and Japanese Laid-Open Patent Application Publication No. 2004-200867, for example).
FIG. 6 is a diagram showing the configuration of a differential amplifier shown in FIG. 4 of Japanese Patent No. 4031447. As shown in FIG. 6, this conventional differential amplifier detects an offset amount and controls the potential of the back gate of the field-effect transistor constituting the differential amplifier, thereby cancelling the detected offset.
Meanwhile, for example, FIG. 2 of Japanese Laid-Open Patent Application Publication No. 2003-332624 discloses a selection circuit which is configured as a differential amplifier in its entirety and to which a plurality of inverting input voltage signals are input and an output voltage of the differential amplifier is input as a non-inverting input voltage signal. In accordance with this configuration of Japanese Laid-Open Patent Application Publication No. 2003-332624, a signal having a lowest voltage is selected from the plurality of inverting input voltage signals and is output through a voltage follower.